Ultrasonic generator



51181 XR :3,157,151 f' Nov. w64 R. H.WH1TTAKER ETAL v 3,?57353 ULTRASONIC GENERATOR Filed April 25, 1962 5 Sheets-Sheet l I JohgYTyhompson Nov, 17, 3964 R. H.WH1TTAKER ETAL 357y35 ULTRASONIC GENERATOR Filed April 25, 1962 5 Sheets-Sheet 2 F g. S

Nov. 17, 1964 R. H. WHITTAKER ETAL 3,157,355@

ULTRAsoNIc GENERATOR Filed April 25, 1962 Sheets-sheet 5 F ig. S

United Staates Patent t assurer urrnasoruc restaurieren The present invention relates to a mechanical resonator and, more specifically, to a mechanical resonator which is resonant at a plurality of frequencies.

Mechanical type resonators or vibrator elements are utilized to generate air compression waves or control the devices remotely. Fthese are commonly used to control television sets, opening and closing garage doors and could be used in various other remote control applications. In patent application, Serial No. l7(l,l57, led January 3l, 1962, in tire name of Arthur Nelkin, Robert A. Lester, Robert H. Whittaker and lohn H. Thompson there is disclosed a new and improved mechanical resonator or vibrator. The resonator disclosed therein operates in a rlexural mode with a plurality of nodal diameters and it has been discovered that this resonator produces relatively high Qs with a relatively low loss to the mounting means of the resonator, The embodiment of the invention disclosed in the above cited patent application is actuated by imparting energy to the surface of the resonator preferably at the outer peripheral edge to provide the ultrasonic signals desired. The embodiment illustrated in the above-mentioned application is specifically illustrated as a disc, but could be a cylinder or plate or other configuration.

ln previous ultrasonic remote control systems, the transmitter generally provides two signals of two predetermined frequencies so that the receiver can operate or e responsive to these two discrete signals. Some remote transmitters also utilized for discrete signals have four sparate ultrasonic frequencies. For each ultrasonic signal in these transmitters, it was necessary to utilize a separate resonator for each ultrasonic frequency so that the receiver may be responsive to the two separate ultrasonic frequencies.

Accordingly, it is an object of the invention to provide a new and improved mechanical resonator which is resonant at a plurality of predetermined frequencies.

A further object of the invention is the provision of a new and improved ultrasonic generator utilizing a single flexural mode vibrator for generating two ultrasonic signals havin(y two distinct predetermined frequencies. v

lt is a further objectot` the invention to provide a flexural mode resonator which can produce at least two ultrasonic signals having different predetermined frequencies and having relatively large amplitude and duration.

A mechanical resonator embodying the present invention includes a flexural mode vibrator' having a plurality of nodal lines and more specically intersecting nodal lines. The vibrator includes a mounting means which is connected to the vibrating element so that a minimum of energy will be dissipated from the vibrator through the connection of the mounting means to an external base or housing. ln addition, the resonator has at least Fatented Nov. l?, 'ld

ice

one dissymmetry portion. This results in the vibrator having two resonant frequencies so that when energy is imparted to one predetermined area in the vibrator a signal having a first frequency will be generated by the vibrator whereas when energy is imparted to the vibrator at another predetermined area a second signal will be generated having a second predetermined frequency. Further, if energy is imparted to the vibrator at still other predetermined portions between the first and second predetermined areas the generator will produce a signal of the first predetermined frequency and the second predetermined frequency.

These and other advantages of this invention will be more clearly understood from the following description when taken in conjunction with the accompanying drawing, in whic.

FIGURE l is an isometric view of an embodiment o the invention;

EEG. 2 is an elevation view of the generator illusrated in HG. l;

3 is a side elevation View of the generator illustrated in FIG. 2;

FIG. 4 is a plan view of the generator illustrated in FIG. 2;

FIG. 5 illustrates nodal diameters and planes of actuation of the generator shown in FlGS. l to 4;

FlG. 6 is another plan view illustrating nodal diameters of the generator illustrated in FIG. 2;

FG. 7 illustrates nodal diameters and planes of actuation of the generator illustrated in FEGS. l to 4;

FG. 8 is another plan view illustrating nodal diam eters of the generator illustrated in FIG. 2;

9 illustrates nodal diameters and planes of actuation of the generator illustrated in FIGS. l to 4;

FIG. l() is an isometric view of another embodiment of the invention; and

FIG. 1l is an isometric view of still another embodis ment of the invention.

In the above-mentioned patent application, Serial No. 170,157, tiled January 3l, 1962, in the name of Arthur Nelkin, Robert A. Lester, Robert l-I. Whittaker and John H. Thompson, there is disclosed an ultrasonic generator for producing ultrasonic signals. This generator utilizes a flexural mode vibrator, having a plurality of nodal diameters, to produce by the vibrations thereof ultrasonic signals. ln this flexural mode vibrator, the mounting means is a pin which is located at a point on the surface of the vibrator so that equal and opposite vibratory forces are applied to this pin so as to provide an undamped connection between the vibrating disc in the mounting pin. Being located in the center of or concentric with one of the circular surfaces, the vibratory forces projected on the pin are equal and opposite, and since the pin is integral with the vibrator the forces are applied to the pin without any damping so that the forces reaching the pin will not be unbalanced. As such the free end of the mounting means or pin can be mounted by any conventional connection without losses of energy through the mounting means, since energy imparted to the disc is retained in the disc due to the cancellation alfordcd by the concentric mounting and the undamped connection with the resonator.

ln the present invention, as shown in FIGS. l and 3, a generally similar vibrating plate or member 1l) is utilized.

(rj The embodiment illustrated therein comprises a vibrator 10 comprising a circular plate or cylinder 1l having an upper circular planar surface l2 and a lower planar surface 13 which is circular and parallel to the upper circular planar surface i2., Extending between the upper and lower surfaces 12 and 13 is the cylindrical side surface 14 which is normal to surfaces 12 and lf3, A circular mounting pin i6 extends downwardly from and is concentric with the lower surface 1.3. The mounting pin f6 is integral with the disc il so that tl e tiexural mode vi,- brating forces from disc il. are applied to the pin i6, are undamped and are equal and opposite. By having the pin 16 as the integral undamped connection with the surface 13, the energy applied to the pin 16 prevents the energy from passing out through the mounting threads 17 of the pin 16. This enables the relatively large amount of the energy imparted to the disc to be converted to ultrasonic signals since no energy loss occurs empty at the mounting threads i7 or any other connection at the free end of pin 16. This mounting is the same as that described in the above patent application. For illustration purposes, as shown in FlG. l and EEG. 3, there is disclosed a mounting base 20, aviug u threaded aperture 21 for receiving the thread 17 of the mounting pin f6. The upper surface of the base Z0 is based a distance Si from the lower surface i3 rom the disc li. if the upper surface of the base is of any appreciable size compared to surface 13, and is relatively close to the lower surface 13 optimum performance will be realized when .this distance is equal to an odd quarter wavelength or any multiplier thereof of the frequency of vibration of the disc. More specifically, the distance in free air Si shoulr not, for optimum performance, be an even quarter wavelength of the frequency of the vibration of the disc since this would tend to cancel and provide a loss of energy transmitted ,by the vibrations.

In t e abovementioned patent application, the reso nator described there?A was actuated by striking the disc to thereby set the disc into vibration in the flexural mode with two nodal diameters which are located at from the point at which the disc was struck. This produced an ultrasonic signal in the range of l0 to 100 kilocycles at a predetermined frequency. in the embodiment of the present invention illustrated in the drawing, one or moreV holes are drilled inwardly to form a geometrical and mass dissymmctry in the cylinder. In so doing, the flexural mode disc is capable of producing two signals at two different frequencies depending upon where the disc is struck. lf more than one hole is drilled in the side surface i4, it should be located at from the other holes. The embodiment illustrated in FIG. l employs four radially disposed holes located at 90 from each other on the surface of the cylindrical side surface Lt'. These holes are illustrated by numeral l5 as shown in FG. l.

In the embodiment shown in ilG. l, an actuating means 40 includes three separate actuating members di 43 and t5 having metallic strikerelcxncnts 42, dit and mounted thereon. The actuating members lli, d3 and i are leaf springs and preferably have a spring constant so that with the metallic striker elements 42, dit and t6 being positioned a predetermined distance from the side surface 14 so that when the springs 4i, 43 and L35 are moved a predetermined distance away from disc Ztl they will impart a single actuating blow to the disc to set the disc into vibration. If the disc is actuated ,by the striker element 42, the disc or plate El will be set into a iiexural mode vibration having two nodal diameters d1 and (l2 as shownuin FIG. l and FlG. 5. fected thereby will have a single frequency predetermined by the dimensions of the device. In order to actuate the disc 11 into vibration having nodal diameters d1 and d2, the energy can be imparted to the disc or the disc can be struck, virtually at any point wherein the planes Pi and P2, as shown in FIG. 5, cross the disc l1. rfhis is illustrated in FlG. 5 by the actuating areas Rl and R2. If

The ultrasonic signal ef` y only one hole is drilled, these areas of cnergization R1 and RZ remain the same and so long as energy is imparted in or on these rectangles, to the disc i1, the frequency of the signal generator thereby will be a predetermined trequency depending upon the depth and the number of holes i5. The dise 3i should be struck near the peripheral surfaces ld to provide maximum output. The plane Pi is a plane which passes normal to the surfaces i2 and i3 of the disc and intersect or. pass through the center of the holes i5. These planes are located at 90 from each other as are the rectangular areas Rl. and lZ. rfhe nodal diameters d1 and (I2 pass through the center "of th-eperipheral surfaces 1d midway ,between and parallel to the planar surfaces i2 and 13, and intersect in the center or the disc. As shown in FIG. 5 and FG. 6, the nodal diameters d1 and d2 are located at 90 to the planes Pl and PZ.

if it is desired to actuate another signal having a different frequency than the signal described in the above paragraphenergy is imparted to the disc by way of the spring letf t5 and the striaer element i6 striking the disc preferably by a single blow to impart energy thereto. When the disc slt is actuated by the striker element 46, another signal is produced by the disc having a lower frcquency than the previously described signal. The vibratiens resulting from the striker 26 have nodal diameters d3 and d which are midway between and parallel to the planar surfaces l2 The nodal diameters d3 and dr are located in the same plane and are positioned at 90 with each other. As shown in FIG. 7, these nodal diamod ters pass through the center of the apertures or holes l5 which are also located midway between and parallel to the planar surfaces i2 and As shown in FG. 8, the leaf spring 45 and the striker are positioned so that the striker $6 contacts the disc at a point which is located in a plane P3. The planes P3 and P4, as shown in PEG. '7, form actuating arcas R3 and R4 at the intersection of disc il.. The planes P3 and P4 are normal to the surfaces 12 and i3 so as to form rectangular actuating areas R3 and The planes P3 and Pd' are located at 90 to each other and intersect at the axis of the disc. Planes P3 and Pd' are located at 45 to planes P?. and P2. When energy is imparted to the disc in actuating areas R3 and R4, vibrations will be set up with a tiexural mode with two nodal diameters d3 and d4. Although the embodiment in the drawing illustrates four holes or portions of dissymmetry, only one hole need be drilled to produce two different frequencies by the same disc. As shown in FlG. 7 and FG. 8, the striker element strikes the disc at a point on the rectanguia area R3 and hence sets up vibrations with the nodai diameters d3 and d. If the cnergv is applied near the center of the disc adjacent the intersection of R3 and R4, very little energy will bc imparted in the form of vibrations to the disc. For optimum etliciency and performance, the disc should be actuated in the outer edges of the rectangular areas R3 and R-t near surfaces 1d. This is likewise true of the actuating areas R1 and R2. By setting the disc llt into vibration by imparting energy to the actuating areas R3 and R4, the flexural mode vibration set up will have a frequency substanf tially lower than the 'frequency of the vibration set up by actuating the disc in actuating areas R1 and R2.

Hence, it is seen that, by drilling inwardly extending holes from the peripheral edge surfaces le, towardthc axis of disc il, a single disc or vibrator can be employed to ktransmit two ultrasonic signals. As shown in Pl'G. l,

ythe striker element lo actuales the discy il. by striking clement on the area R3. The same signal could be pro duced by actuating the disc by striking the clement in the area R4. The arca R3 islocated at 45 to the area Rl and the plane Pi. lf it is desired to produce a signal having two discrete frequencies, that is, the frequency pro duced by striker 46 and the frequency produced by striker 52, the actuating member with leaf spring 43 and actuating striker element 44 are employed to strike the disc.

As shown in FIG. 9, to produce a signal having both frequencies of substantially equal magnitude, such as by striker element dei., the disc is actuated by applying energy to the actuating areas R5 and R6. Actuating areas R5 and R6 are described by the intersection planes P5 and P6 with disc ll, respectively, which are located at 90 to each other and are normal to the surfaces l2 and i3. The plane F5 is located midway between planes Pl and P3 that is, it is 221/2 from planes Pl and P3. P6 which forms actuating area R5 is located at 90 to and normal to plane P5 and is midway between planes P2 and lfi. That is, it forms a 221/2o angle with planes PZ and P4.

signals will be produced one having the frequency of a signal that would be produced by actuating the disc in actuating areas Ri and R2 and the other signal having the frequency of actuating the disc in actuating areas R3 actuating area R5 and actuating area Rl, so that for example the striker element i4 is positioned closer to striker element 42 than to striker element d6, there will be two frequencies produced, however, the higher frequency will have a greater amplitude and about the same ringing time.

In drilling the disc radially with a single hole or four quadrant holes as described above, double mode operation is obtained so that two signals, one having a frequency f1 is below the undrilled disc frequencyj and the other signal has a frequency f2 which is above the undrilled frequency fo. Increasing the hole depth increases the separation of f1 and f2 as shown in the tables below. When the disc is drilled through the surfaces l2 or 13 actually off-center of the disc axis, as by a hole 19, the two frequencies f1 and f2 are both below fo and their separation increases with the hole depth, hole diameter and number of holes. lf only one hole .t9 is drilled oil-center in disc il the Q of the device will be lowered. If a similar hole is positioned an equal distance from the center and on the same diameter the Q will not be changed.

lf a hole f3 is drilled actually through the surface l2, as shown in FlG. ll, of the disc having no radial hole, the frequency of fo is reduced. if there are radial holes l5 in the disc li, as shown in PEG. ll, this hole l@ reduces f1 and f2 equally. When the hole f3 is drilled in a disc having the radial holes or hole l5, although the frequencies f1 and f2 are lower, the separation or beat frequency between frequencies f1 and f2 remains constant when this operation is carriedout. When hole 19 is drilled off the axis of the disc, the separation afforded thereby between frequencies f1 and f2 increases with the hole depth as shown in the following tables.

A relatively high Q material should be used to construct the discs (at least 5,000-l0,000) to provide a usable output. The mass dissymmetry of disc l1 formed by holes l5 and i9 can be accomplished by grooves, Illing the surfaces, some discontinuity of mass or material other means in the disc l to produce two signals from the same vibrator. lf only one diss ,fmiuetry of mass portion is formed, the Q of the system will be lowered somewhat. lf a second dissyr .inetry portion is formed it increases the frequency separation. This second dissymmetry portion should be similarly formed on the diametrically opposite side of the disc axis or at 90 to the first portion (and equally spaced therefrom) in order to enable production of two separate frequencies. lf this second -portion is not similar and equally spaced from the disc axis, and at or 130 from the first dissymmetry portion there will be coupling between the two frequencies or two modes and any signal produced by the disc will have portions of both frequencies.

The fell wing are samples of flexural discs constructed that produced two signals having two separate frequencies. All these discs had a Q of at least 20,000 with the distance Si being approximately one quarter wavelength of the undrilled resonant frequency of the disc. lilexural disc with single radial hole (]0=frequency of undrilled disc; f1 and f2 being the two frequencies caused by the dissymmetry of mass):

Flexural disc with 4 radial quadrature holes:

lfisc material=sarne as above Disc dlaineterzsaine as above -ss=same as above Post diameter-:same as above Post length-.same as above fg=33,377 cps.

Hole diameter=.l25 inch Table L Frcqzteizcy Characteristics 0f Disc Wz'h Radin! Holes Hole fz-fr, Beat 1+ 2/2 Dise Dench, fr, cps. Frequency, ferire.

Inches c.p.s.

. OS-i 33, 527 33, 398

. (iQ-l 33, 073 668 33, 407

Table .Zr-Frequency Characteristics of Disc With Olie Axial [101e Flexural disc with two axial holes located equidistant from center on a common diameter:

Disc inaterial=same as on Table l Disc diameter-same as on Table l Disc tliicknesszsaine as on Ta le l Post diameter=sa1ne as on Table l Post length=same as on Table l f0=33,370 cps.

Diameter of hole=as tabulated Distance from hole centers to aXis=.500 inch Holes drilled through il Table 3A. Effect 0f Axial ,Tuning Gil Ille Bise Axis for Discs Wil/l Their Bent Frequencies Determined by Radial Holes llexural disc with one radial hole:

anni non Depor)v fl-, B01-Lt Inches fr, c.p.s. f2, e.p.s.- lircqueney,

' eps.

.t 311 32,917 ltltl.-..... 307 32, 257

Flcxural disc with four radial holes.

Dise inatcrial=sa1ne as on Table 1 Dise diamctcrz. 'ne as on Table l Bise tl'iitfines ame ns on Table l Post timmeren-saine as on Table l Post le .glhzsnme as on v'lalile l 33,380 eps.

Diameter of radial holes-1.125 inch Depth of radial holeszlSS inch Axial tuning hole on disc axis diameter-1.251 incli Axial Hole Depth,

lnc'ncs' f1, e.p.s. fr, c.p.s.

c.p.s.

32, 921 33,830 ins s i, use 33, ssi .are 126 s3, ois la si, 75s se, ons :no

fab/e 33.-E1jfect of Axial Trini/1g on lire Dis-c Axis for n ,Disc Wit/1 Ils Bezit Frequency Deiemiiued by Axial Holes Disc identical to that on Table 2 Axial timing on disc axis Axial Hole Depth,

Inches f1, eps.

All the above Vibrators had a Q of at lea it 26,9011 mien tested in tree air without a housing. C'ttested having Qs of atleast 20,4330 where the or symmetry of mass of the disc was caused by a w in the material, by ling n portioiroi the disc etc., lto thereby produce two separate frequencies from the disc. lt will 'oe noted tlcet these frequencies are not overtones.

Although this invention has been described in conncetion with this specific embodiment, it will he apparent to those skilled in the art that changes and arrangements in parts can be made to suit the requirement without departing from the sp' 'it and scope ofthe invention.

We claim as our invention:

l. A mechanical resonator comprising, a vibrator resonant in a flexural mode having a plurality of nodal lines, said vibrator having a surface and a second suriace opposite so d iirst surface, mounting means supporting said vibrator. said vibrator having a dissymmetry portion and means to actuele said vibrator into vier-ation in a flexural mode with a plurality or" nodal lines.

2. A mechanical resonator comprising, a vibrator resoI nant in a tlexural mode having a plurahty of intersecting nodal lines, said vibrator having' a rst surface, and s sccond surface opposite said iirst surface, mounting means for supporting said vibrator centrally of said llrst surface, said Vibrator having a dissyminetry portion and means to actuate d vibrator into Vibration in a ilcxural mode with a plurality of intersecting nodal lines.

3. A mechanical resonator comprising, a vibrator reso nant in a l ural inode l' a plurality of nodal lines, c tor having a.' t sull-ace, and a second surface 3 said llrst surface, mounting means supporting said vibrator centrally ot' said irst surface, an aperture extending inwardly from the surface of said Vibrator, and ineens to actunte Said vibrator into vibration in a llexural nto-:ie with a nh vity or" nodal lines.

4. A mee" al resonator comprising, a vibrator resonant in n tici-tu mode having a plurality of intersecting nodal lines, said *rater Laying a first surface and a second surface ein' te said first surface, nioun ng means supporting said vibrator, a dissymmetry portion on the surface of l vibrator, d in .ins to actuate said yibrator into vibration in a il-. ral mode with a plurality of intersecting nodal lines.

5. A mechanical r later com' rant in :t n-.xural .e haring a p nodal lines, said l having a li surface and a sccond sul said rst surf c, an axis normal to said Fast surface and passing through the inter :ction said nodal lines, mounting means supporting said vibrator centrally of said iirst s riace, said vibrator having a clissymmetry portion, means for applying energy to said vibrator at e. predetermined rercr said vibrator into Vibration in a rali-t" ot nodal liY the plane mined reference point and said hy the said dissynnnetry portion and. said axi angle of N times forty-iive degrees where N equals any odd integer.

6. A mechanical resonator comprising, a vibrator resonant in a .flexural mode having a plurality of nodal diameters, said Vibrator havin" a pair of parallel circular planar surfaces with periL ieral edge surfaces extending therebetween a pin extending out'ivardly from and concentric with one of lsaid planar surfaces, said pin being integral with said vibrator, a hole extending inwardly from. said peripheral side surfaces toward the axis of said vi'orator, means for applying mechanical energy to said. vibrator at a predeter ined point on the surface thereof 'to actuate said vibrator into vibration in a lexural mode with a plurality of nodal diameters, predetermined point and said s deiining a plane positioned at an aA le of ll times forty-iure degrees with a second plane denn-ed by the center oi said hole and said axis i nere N equals any odd integer and means for applying enc to said vibrator in sai-a second plane to actuele sind Violator into vibration.

7. A transmitter for generating ultrasonic s'cnals at a plurality of predetermined frequencies, comprising, a cylindrical vibrator resonant in n flexural mode having a plu rality of nodal diameters, said vibrator having a first planar `surface and a second planar surface opposite and parallel to said rst planar surface, cylindrical side surfaces extending between seid lirst and said second surfaces, a moun. ng pin, connecting means providing an ung. a 'vibrator reso- .'.y et intersecting being atan damped connection between the :enter of said first surface y Q by the center of one of said holes and said axis, and means for applying energy to said vibrator on the surface tliercoat another reference point, said other reference point being located in a piane defined by the `center of one said holes and said axis.

8. A transmitter for generating ultrasonic signals at predetermined frequencies comprising, a vibrator resonant in a flexural `mode having a plurality of intersecting nodal lines, said vibrator having a first surface and a second surace opposite said rst surface, side surfaces beiween said first and second surfaces, mounting means, connecting .sans for providing an undnm-ped connection between said mounting means in the center of said rst surface, a hele extending inwardly from said side surface, means for applying energy rto said vibrator at a predetermined reference point on the surface `therefor to actuate sai-d vibrator into Vibration in a iiexural mode with a plurality of intersecting nodal lines, said reference point located in a plane including the axis of said vibrator which defines u an angle with a plane defined by the axis of said Vibrator in the center of -said hole equal to 1z 45l22-5 where 1 1 equals any integer or zero.

References Cited in the le of this patent UNITED STATES PATENTS OTHER REFERENCES Proceed-ing: American Academy of Arts and Sciences, vol. 63, No. l, April 1928, Magnetostriction Oscillators, G. W. Pierce, pages 1-47. 

6. A MECHANICAL RESONATOR COMPRISING, A VIBRATOR RESONANT IN A FLEXURAL MODE HAVING A PLURALITY OF NODAL DIAMETERS, SAID VIBRATOR HAVING A PAIR OF PARALLEL CIRCULAR PLANAR SURFACES WITH PERIPHERAL EDGE SURFACES EXTENDING THEREBETWEEN A PIN EXTENDING OUTWARDLY FROM AND CONCENTRIC WITH ONE OF SAID PLANAR SURFACES, SAID PIN BEING INTEGRAL WITH SAID VIBRATOR, A HOLE EXTENDING INWARDLY FROM SAID PERIPHERAL SIDE SURFACES TOWARD THE AXIS OF SAID VIBRATOR, MEANS FOR APPLYING MECHANICAL ENERGY TO SAID VIBRATOR AT A PREDETERMINED POINT ON THE SURFACE THEREOF TO ACTUATE SAID VIBRATOR INTO VIBRATION IN A FLEXURAL MODE WITH A PLURALITY OF NODAL DIAMETERS, SAID PREDETERMINED POINT AND SAID AXIS DEFINING A PLANE POSITIONED AT AN ANGLE OF N TIMES FORTY-FIVE DEGREES WITH A SECOND PLANE DEFINED BY THE CENTER OF SAID HOLE AND SAID AXIS WHERE N EQUALS ANY ODD INTEGER AND MEANS FOR APPLYING ENERGY TO SAID VIBRATOR IN SAID SECOND PLANE TO ACUTATE SAID VIBRATOR INTO VIBRATION. 